Treatment of food products



Patented June 13, 1939 UNITED STATES PATENT OFFlCE No Drawing.Application March 18, 1937, Serial No. 131,553

Claims.

This invention relates to improvements in methods for treating foodproducts, being particularly directed to a treatment for conditioningfood products prior to quick freezing thereof by 5 means of the brinespray or analogous methods.

In present freezing operations, particularly those wherein the freezingmedium is a brine spray functioning by direct contact, certain foodproducts, particularly fruits, vegetables and open cuts of meat, absorbexcess of salt or other chemical reagents applied in the freezing mediumand further, by virtue of the porosity or perviousness of the surfacemembranes thereof, permit of the formation below the surface of enlargedice crystals incorporating the freezing chemical reagent, both of whichproperties lead to the production of improperly frozen andunsatisfactorily appearing products.

Broadly, it is an object of this invention to provide for a preliminarytreatment prior to quick freezing of fruits, vegetables or open cuts ofmeat, whereby there is imparted to the surface membranes thereof arelatively fluid impervious shell formation.

Specifically, it is an object of this invention to apply a preliminarytreatment prior to quick freezing of fruits, vegetables and open cuts ofmeat, whereby there is imparted to the aforesaid products an imperviousshell or skin effect, through the disposition of minute frozen particlesin the pores of the surface membranes, replacing the fluid normallytherein, such effect being essentially restricted to an infinitesimallythin surface zone. 35 These and other advantages, capabilities andfeatures of the invention will appear from the subjoined detaileddescription of one specific embodiment thereof.

In carrying out my process reference, for example, being had to thefreezing of peas as a representative vegetable, the same, after shellingand grating, are' cooled to approximately the temperature of 36 F. bysubmersion in or spraying with water at a temperature of about 34 F.,the product, upon being removed from the treating station having asurface film of moisture or liquid.

With respect to certain food products as, for example, cauliflower orthe like, where possibility exists of action and attack through enzymesand catalous growths, it is desirable, prior to the chilling step aboveoutlined, to blanch by dipping the same for a short period in a hotsolution at approximately boiling point for a very short period, so thatsuch enzymes and catalous growthswill be killed.

Thereafter, the cooled or chilled product whose surface membrane issurrounded by a film of liquid, is passed into a chamber, as, forexample, on a pervious purveyor belt or disposed on wire mesh shelves,where, for a period of about five minutes or less, they are subjected toa cold air blast at a pressure of seven or eight pounds at the blower,the temperature of the air blast being from zero to minus 10 F., and thechamber being maintained at atmospheric temperature and at a temperatureof about 0 15.

In this step, the product is contacted by the blast on its surface, withthe result that the excess chilling liquid forming the surface film iseliminated by dispersion and/ or evaporation. As the surface liquidforming the film is dispersed or evaporated by the blast, the surfacemembrane will consist essentially of solid matter plus the minute fluidparticles normally present in its capillaries or pores. The cold blastat the low temperatures and for the short period involved causes afreezing of such minute fluid particles in the pores of the membrane,thereby causing the production of a substantially hard butinfinitesimally thin impervious surface formation in the nature of ashell.

By virtue of the formation of this shell penetration by brine fluid inthe subsequent quick freezing operations as by spraying or the like, iseliminated, while at the same time, however, heat exchange throughpenetration into the interior of the product is readily carried out.

It is obvious that various changes and modifications may be made to thedetails of this process without departing from the general spirit of theinvention as set forth in the appended claims.

I claim:

1. A method of treating food products prior to quick freezing,comprising chilling the same by contact with a liquid, and subjectingthe chilled product to a blast of air at freezing temperatures todisperse and evaporate substantially all the liquid on the surface ofthe products and to form minute crystals in the surface pores, therebyto provide a substantially impervious shell formation.

2. A method of treating food products prior to quick freezing,comprising chilling the products by contact with a liquid, whereby aliquid surface film is formed on the product, and subjecting the chilledproduct to a blast of air at freezing temperatures to disperse andevaporate substantially all the liquid forming the surface film and toform minute crystals in the pores of the surface of said food products,thereby to provide a substantially impervious surface shell.

3. A method of treating food products having a pervious surface, priorto quick freezing thereof, comprising bringing the food products to atemperature slightly above freezing through contact with a liquid, andsubjecting the food product to a blast of air for a short period atfreezing temperatures, to disperse and evaporate substantially all theliquid present on the surface of the food product and to form minutecrystals in the surface pores of the food product.

4. In a method of treating food products having pervious surfacemembranes, the step after chilling in liquid and. prior to quickfreezing by brine contact, comprising discharging air at freezingtemperatures upon the food products to disperse and evaporatesubstantially all free liquid from the surface of the food products andto form minute crystals in the pores of the surface membrane.

5. In a method of treating food products having pervious surfacemembranes, the step after chilling in liquid and prior to quickfreezing, comprising discharging upon the food products an air blast ofvelocity to remove substantially all free liquid from the surfacethereof and at a temperature and for a period to form minute icecrystals in the pores of the surface membrane, thereby to provide asubstantially impervious surface membrane.

CHESTER J. CONN.

